Hello,
I''ve been using Rails for years, including has_many :through and eager
loading, but this one has me stumped.
The problem is that Active Record is only eager-loading the first of
many records. Here are the models (note set_table_name for a legacy
schema):
class Tag < ActiveRecord::Base
set_table_name ''tag''
end
class DishTag < Tag
has_many :dish_taggings, :foreign_key => ''tag_id''
has_many :dishes, :through => :dish_taggings
end
class DishTagging < ActiveRecord::Base
set_table_name ''dish_tag''
belongs_to :dish
belongs_to :dish_tag, :foreign_key => ''tag_id''
end
class Dish < ActiveRecord::Base
set_table_name ''dish''
has_many :dish_taggings, :foreign_key => ''tag_id''
has_many :tags, :through => :dish_taggings, :source => :dish_tag
end
In the controller, I eager-load like this:
@tags = DishTag.find(:all, :include => {:dish_taggings => :dish})
Here are the resulting queries (with traces thanks to the query_trace
plugin):
DishTag Columns (1.2ms) SHOW FIELDS FROM `tag`
DishTag Load (0.9ms) SELECT * FROM `tag` WHERE ( (`tag`.`type`
''DishTag'' ) )
app/controllers/tags_controller.rb:5:in `index''
DishTagging Load (6.9ms) SELECT `dish_tag`.* FROM `dish_tag` WHERE
(`dish_tag`.tag_id IN
(58,60,61,62,63,79,81,82,83,90,91,93,94,96,97,99,102,104,106,109,110,114,120,121,122,123,124,125,126,127,131,132,133,135,136,137,138,139,141,143,144,145,146,147,149,150,153,154,157,158,161,166,178,181,184,199,229,232,235,238,259,262,277,283,298,301,304,307,310,313,322,331,334,337,340,343,346,352,355,358,361,364,370,373,376,379,391,394,400,403,406,409,412,415,418,436,439,442,445,448,451,454,457,481,484,532,535,547,550,553,556,559,562,568,580,706,721,724,730,733,736,739,742,745,748,751,754,757,760,763,766,769,778,781,784,787,790,793,796,799,802,805,808,811,814,817,820,823,826,829,832,835,838,841,844,847,850,853,856,859,862,865,868,871,874,877,880,883,886,889,892,895,898,901,904,907,910,913,916,919,922,925,928,934,937,940,943,946,949,952,955,958,961,964,967,970,973,979,982,985,988,991,994,1003,1006,1009,1012,1015,1018,1021,1024,1027,1030,1033,1036,1039,1042,1045,1048,1051,1054,1057,1060,1063,1066,1069,1072,1075,1078,1081,1084,1087))
app/controllers/tags_controller.rb:5:in `index''
DishTagging Columns (1.2ms) SHOW FIELDS FROM `dish_tag`
Dish Columns (2.0ms) SHOW FIELDS FROM `dish`
Dish Load (0.4ms) SELECT * FROM `dish` WHERE (`dish`.`id` = 209)
app/controllers/tags_controller.rb:5:in `index''
Notice that in DishTagging Load, the first foreign key in the list is
58. As it turns out, there is only one DishTagging witth tag_id 58,
and its dish_id is 209. Now look at Dish Load: it''s loading dish 209
and nothing else.
So, this leads me to believe that only the first related record is
being eager-loaded. Sure enough, when I iterate, Active Record loads
each dish individually except for dish 209.
Any thoughts on why this is happening? I''ve never seen this problem
before. I''m guessing it has something to do with all the stuff
I''ve
had to override in the model configs (e.g. table names and foreign
keys.) But I''m not getting any exceptions.
--
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.
Frederick Cheung
2010-Feb-15 08:49 UTC
Re: has_many :through eager loading only loading one record
On Feb 14, 11:24 pm, Jarrett <jarrettco...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> > Notice that in DishTagging Load, the first foreign key in the list is > 58. As it turns out, there is only one DishTagging witth tag_id 58, > and its dish_id is 209. Now look at Dish Load: it''s loading dish 209 > and nothing else.Dumb question: Are their dish_tags with tag_id 60,61,62 etc. What is their dish_id ? Fred -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
Frederick Cheung
2010-Feb-15 08:52 UTC
Re: has_many :through eager loading only loading one record
On Feb 15, 8:49 am, Frederick Cheung <frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> On Feb 14, 11:24 pm, Jarrett <jarrettco...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > > > > > Notice that in DishTagging Load, the first foreign key in the list is > > 58. As it turns out, there is only one DishTagging witth tag_id 58, > > and its dish_id is 209. Now look at Dish Load: it''s loading dish 209 > > and nothing else. > > Dumb question: Are their dish_tags with tag_id 60,61,62 etc. What is > their dish_id ? >Another thought - you seem to have some sort of STI thing going on (DishTag < Tag). Does the type column on the tags column contain appropriate values? Fred> Fred-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.